Comments by Jan

  • New products: 16-channel QTR MD reflectance sensor arrays

    New products: 16-channel QTR MD reflectance sensor arrays

    - 31 December 2018

    Thanks for the feedback! Making a version of these with a microcontroller on board has been on the to-do list for a while, and I hope to get to it next year (I'm writing this on December 31).

    - Jan

  • Electrical characteristics of servos and introduction to the servo control interface

    Electrical characteristics of servos and introduction to the servo control interface

    - 27 December 2018

    Hello.

    This is not something to calculate (if you trusted your battery capacity, you could do some calculations based on how long it lasts, but you could only do that for lighter loads since forcing your servo to some max load scenario for a prolonged period would likely destroy it). So, you should just put a current meter in line with your servo and see how much it draws. That would typically show you average current over maybe a tenth of a second or however fast your meter updates. If you want to see the faster peaks, you would need to use an oscilloscope.

    - Jan

  • Continuous-rotation servos and multi-turn servos

    Continuous-rotation servos and multi-turn servos

    - 23 November 2018

    Hi, Gordon.

    I have not heard of such a servo. I don't know if you need the actual feedback and the higher torque you get from typical hobby servos, but perhaps you should look at stepper motors, too (along with our Tic stepper motor controllers: https://www.pololu.com/tic ).

    Please share if you do find anything.

    - Jan

  • Servo control interface in detail

    Servo control interface in detail

    - 20 August 2018

    Peter,

    Yes, there is a control board in the servo that takes the signal you send it, compares it to the position feedback on the servo, and drives the motor appropriately. You can look at our Jrk motor controllers to get more of an idea of what could be going on inside the servo:

    https://www.pololu.com/product/3142

    The Jrk controllers have a lot more interfaces and features than what you would find in typical hobby servos, but the basic idea is the same.

    - Jan

  • Servo control interface in detail

    Servo control interface in detail

    - 14 May 2018

    Your questions are answered in the rest of the post and other screenshots. When the servo gets the control signal pulse, it sends a pulse of power to the motor based on how big the error is. The energizing of the motor (the current pulse) is not ending because the error went away. You can see in the last screenshot that once the servo is in position with no resistance, there are no current spikes corresponding to the control pulses (the last two).

    - Jan

  • New product: VL53L0X Time-of-Flight Distance Sensor Carrier

    New product: VL53L0X Time-of-Flight Distance Sensor Carrier

    - 3 April 2018

    Hello, Santiago.

    Yes, we are planning on that. We have the sensor chip on order, but with the crazy lead times lately, it might still be a few months before we get them.

    - Jan

  • New product: Pololu USB AVR Programmer v2.1

    New product: Pololu USB AVR Programmer v2.1

    - 23 March 2018

    Hi, Brian.

    Please keep in mind this is just an issue when powering the A-Star from the programmer, so the programmer still works fine if the A-Star has its own power source, which you typically have to have, anyway. But it can be convenient, which is why we improved the feature. There are some tricks you can do, like increasing the capacitance on the programmer side or putting a small resistor in line with the power from the programmer to the A-Star. It's not something we would want to do for a production solution.

    In any case, I want your reaction to be, "yay!", not "darn!" when we make better products. If you email us with your order number and reference this comment, we'll send you a couple of the new ones.

    - Jan

  • New products: RoboClaw Solo 30A and 60A Motor Controllers

    New products: RoboClaw Solo 30A and 60A Motor Controllers

    - 19 March 2018

    Hi, Jay.

    What prices, for which controllers, would you consider not to be "so much"? And if you have some reasons for your prices, please share those as that would also help us give you a better answer.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 13 March 2018

    Hi, Robert.

    It sounds like you are trying to put your cells in parallel, which can be tricky, to get a 1.2V, 100Ah pack, and then to somehow boost to 12V, which is going to be very difficult and inefficient. You would be better off putting your cells in series, which gets you straight to 12V, and then the only question is whether the D cells can give you 50A. I don't think they can, and you say you saw 30A peak, which sounds plausible to me. So if you really need 50A, you should figure out how to put the two 10-cell packs in parallel (which, again, is tricky, since you're initially shorting two different packs together). If you need a regulated 12V, you could do 20 or more cells in series to get to about 24V, then regulate that down to 12V. I don't know where to get a 50A 12V regulator that can take 40V in, but it will be way more efficient than trying to boost 1.2V to 12V.

    Separately, why don't you just use a 12V gel cell (lead acid) battery? It's pretty easy to get them with about 10-15Ah capacity, which should be able to do 50A peaks pretty easily, and it wouldn't be much bigger or heavier than a NiMH battery.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 26 February 2018

    Hi, David.

    Did you read the main post? It looks like you did not get the point of the amp vs. amp-hour distinction. (Or maybe it's just a typo in what you posted for your battery spec.)

    In any case, if the battery is lasting a week, it's probably good enough. The main problem is that you are trying to use more energy in your lights overnight than you collect during the day. If you want to use 18W for eight hours and you have only 4 hours to collect that, you would need at least 36W. That would be at 100% efficiency, which for sure you will not have, and for the whole time, not just when you get the most direct sunlight. You probably need at least five times your current solar panel capacity.

    - Jan

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